The invention concerns a nuclear reactor installation with a reactor building which contains equipment and operating rooms and is closed during the operation of the reactor. Equipment rooms are called here those parts of the nuclear reactor installation which contain heavily radiating components and can therefore be entered only with special protective measures, e.g., protective clothing. Operating rooms, on the other hand, are such rooms, in which accessibility is assured operationally, i.e., also in the absence of special occurrences, as testing or maintenance work is to be performed there.
In connection with pressurized water reactors, reactor buildings are known which are partly accessible during the operation of the reactor. Here, a relatively expensive ventilation system takes care that sufficiently clean i.e., radiation-free, atmosphere is available in these accessible parts. The air is here drawn-in from the outside and pushed into the accessible rooms. From there, it flows through leaks, and optionally, through intentional passage openings, into the rooms in which a higher radiation level is permissible and underpressure relative to the accessible rooms is maintained. The air leaves the reactor building finally via filters and optionally, purification equipment with delay sections, decay tanks, etc. For this purpose, an exhaust gas chimney can be used, which serves to ensure sufficiently wide distribution and therefore, dilution of the gases.
Other pressurized water reactors, which are common particularly in the U.S.A, have a reactor building which is completely closed during the operation of the reactor. Here, one therefore gives up quite intentionally the accessibility during operation. The ventilating system can thereby be simplified, of course, as ventilation takes place only outside the operating time of the reactor, when the reactor building is to be opened.